Re: [PATCH 2/2] arm64: Define PAGE_OFFSET using GENMASK_ULL

From: Nick Desaulniers
Date: Wed Aug 02 2017 - 19:19:19 EST


hmm, seems including the definition of GENMASK_ULL causes tons of issues
see definition of UL() macro
defines _AC
token pastes UL on literal when not assembly
so looks like GENMASK_ULL is not ready to be used from assembly

On Wed, Aug 2, 2017 at 4:13 PM, Nick Desaulniers
<ndesaulniers@xxxxxxxxxx> wrote:
> don't forget to include linux/bitops.h now in memory.h
>
> /usr/local/google/home/ndesaulniers/android/kernel-wahoo/private/msm-google/arch/arm64/kernel/head.S:47:8:
> error:
> function-like macro 'GENMASK_ULL' is not defined
> #elif (PAGE_OFFSET & 0x1fffff) != 0
> ^
> /usr/local/google/home/ndesaulniers/android/kernel-wahoo/private/msm-google/arch/arm64/include/asm/memory.h:52:22:
> note:
>
> expanded from macro 'PAGE_OFFSET'
> #define PAGE_OFFSET GENMASK_ULL(BITS_PER_LONG_LONG - 1, VA_BITS - 1)
> ^
> 1 error generated.
>
> On Wed, Aug 2, 2017 at 3:51 PM, Matthias Kaehlcke <mka@xxxxxxxxxxxx> wrote:
>> As is the definition causes an integer overflow, which is expected,
>> however clang raises the following warning:
>>
>> arch/arm64/kernel/head.S:47:8: warning:
>> integer overflow in preprocessor expression
>> #elif (PAGE_OFFSET & 0x1fffff) != 0
>> ^~~~~~~~~~~
>> arch/arm64/include/asm/memory.h:52:46: note:
>> expanded from macro 'PAGE_OFFSET'
>> #define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1))
>> ~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~
>>
>> Use GENMASK_ULL() instead of shifting explicitly, the macro takes care
>> of avoiding the overflow.
>>
>> Reported-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
>> Signed-off-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
>> ---
>> arch/arm64/include/asm/memory.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
>> index 32f82723338a..732d4eed8edd 100644
>> --- a/arch/arm64/include/asm/memory.h
>> +++ b/arch/arm64/include/asm/memory.h
>> @@ -65,7 +65,7 @@
>> */
>> #define VA_BITS (CONFIG_ARM64_VA_BITS)
>> #define VA_START (UL(0xffffffffffffffff) << VA_BITS)
>> -#define PAGE_OFFSET (UL(0xffffffffffffffff) << (VA_BITS - 1))
>> +#define PAGE_OFFSET GENMASK_ULL(BITS_PER_LONG_LONG - 1, VA_BITS - 1)
>> #define KIMAGE_VADDR (MODULES_END)
>> #define MODULES_END (MODULES_VADDR + MODULES_VSIZE)
>> #define MODULES_VADDR (VA_START + KASAN_SHADOW_SIZE)
>> --
>> 2.14.0.rc1.383.gd1ce394fe2-goog
>>
>
>
>
> --
> Thanks,
> ~Nick Desaulniers



--
Thanks,
~Nick Desaulniers